1. Field of the Invention
The present invention relates to a telephone exchange apparatus for executing communication service functions relating to any one of exchanges between mutual extensions, between an extension and a line wire, and between mutual line wires, and more particularly to a telephone exchange apparatus and a control method for the telephone exchange apparatus intended to improve recovery from failure.
2. Description of the Related Art
Hitherto, in office and other buildings, the telephone exchange apparatuses such as a key telephone apparatus and a private branch exchange (PBX) have been widely used. This kind of telephone exchange apparatus contains telephone sets or the like as extension terminals, and enables calls by switching and connecting between the extension terminals and the external network such as a public telephone network, and between mutual extension terminals.
In such a telephone exchange apparatus, if any abnormality occurs in a resource for executing the communication service function, such a resource failure cannot be recognized by a maintenance engineer or the like. Therefore, the telephone exchange apparatus may be left over for a long time while the resource is abnormal, and it often causes troubles in management of the apparatus.
Accordingly, there have been proposed a method of initializing the process by determining resource abnormality and using this abnormal resource (for example, see Jpn. Pat. Appln. KOKAI Publication No. 2000-267869), and a method of releasing, at the time of a call, an illegally used resource by checking whether or nor a resource corresponding to the call is used illegally (for example, see Jpn. Pat. Appln. KOKAI Publication No. 2001-268607).
In these methods, however, the corresponding resource cannot be released if failure occurs in the midst of execution of communication service function. Also in such methods, the normal resource may be adversely influenced if the resource is released or the process using the corresponding resource is initialized during execution of the communication service function.